GPIO 14 (UART Transmit)
|UART0 TXD||SMI SD6||DSI D10||AVEOUT VID10||AVEIN VID10||UART1 TXD|
- Physical/Board pin 8
- GPIO/BCM pin 14
- Wiring Pi pin 15
This pin doubles up as the UART transmit pin, TX. It's also commonly known as "Serial" and, by default, will output a Console from your Pi that, with a suitable Serial cable, you can use to control your Pi via the command-line.
The UART pins are useful for setting up a "headless" Pi (a Pi without a screen) and getting it connected to a network.
UART can be used to talk to Serial GPS modules or sensors such as the PM5003, but you must make sure you disable the Serial Console in raspi-config first.
On the Pi 3 and 4 the UART is, by default, used for Bluetooth and you may need to add "dtoverlay=miniuart-bt" to "/boot/config.txt" to achieve a stable.